Field of the Invention
The present invention relates to a printing apparatus and leakage detection method, and particularly to a printing apparatus in which a printhead is attached to a carriage and printing is performed by the printhead while the carriage is reciprocally moved, and a leakage detection method of the apparatus.
Description of the Related Art
In a printing apparatus in which a printhead mounted on a carriage is exchangeable by the user, the printhead deteriorates with time when it has been used for a long term, so an internal circuit of the printhead malfunctions, and a current leakage occurs from a head voltage supply line. Consequently, a print failure occurs. To detect this leakage, a function called leakage detection can be used. By this leakage detection, it is possible to detect a failure of the printhead, notify the user of the failure, and prompt the user to exchange the printhead. As a result, a print failure can be prevented. As disclosed in, for example, Japanese Patent Laid-Open No. 2005-305966, the conventional leakage detection uses an arrangement in which power to be used in normal printing and power to be used in leakage detection are supplied through the same power supply line.
Since, however, the conventional leakage detection uses the same power source as that used for normal printing, the detection requires a time for charging electricity to a large capacitor formed to stabilize the voltage in the same manner as that for normal printing. This prolongs the time necessary for leakage detection.
During a printing operation in which a load is applied on the printhead, therefore, performing time-consuming leakage detection is unrealistic from the viewpoint of throughput. Accordingly, no related art explicitly discloses a means or sequence for detecting an abnormal state progressing in the printhead during a printing operation. Also, no publication pertaining to the conventional leakage detection explicitly specifies the activation timing of leakage detection as a printing apparatus.